Conreal curvature adjustment ring

ABSTRACT

Surgical apparatus for inserting a plastic, split end, adjusting ring into the stroma of the cornea of the eye wherein the adjusting ring includes, as a part thereof, a dissecting head to part the stroma and provide a pathway for the adjusting ring as the ring is rotated. The ends of the adjusting ring are moved to change the shape of the cornea to a desired shape in accordance with the desired visual correction after which the ends of the adjusting ring are fixably joined to maintain the desired shape.

RELATED PATENTS AND APPLICATIONS

This application is a continuation of U.S. Ser. No. 566,687 filed Aug.13, 1990, now abandoned, which is a divisional of U.S. Ser. No. 357,700,filed May 26, 1989, now U.S. Pat. No. 4,961,744, which is a continuationof U.S. Ser. No. 62,790, filed Jun. 15, 1987, now abandoned, which is acontinuation-in-part of U.S. Ser. No. 336,919 filed Jan. 4, 1982, nowU.S. Pat. No. 4,452,235, and a continuation-in-part of U.S. Ser. No.579,480 filed Feb. 13, 1984, now U.S. Pat. No. 4,671,276, and acontinuation-in-part of U.S. Ser. No. 10,400 filed Feb. 3, 1987, nowU.S. Pat. No. 4,766,895.

This invention relates to and incorporates herein by reference certainaspects of U.S. Pat. No. 4,452,235 issued Jun. 5, 1984, and U.S. Pat.No. 4,671,276 issued Jun. 9, 1987.

BACKGROUND OF THE INVENTION

This invention relates overall to an apparatus for adjusting the shapeof the components of the eye and more particularly to making fixedchanges in the corneal curvature. Deviations from the normal shape ofthe corneal surface produce errors of refraction in the visual process.The eye in a state of rest, without accommodation, focuses the image ofdistant objects exactly on the retina. Such an eye enjoys distinctvision for distant objects without effort. Any variation from thisstandard constitutes ametropia, a condition in which the eye at rest isunable to focus the image of a distant object on the retina. Hyperopiais an error of refraction in which, with the eye at rest, parallel raysfrom distant objects are brought to focus behind the retina. Divergentrays from near objects are focused still further back. In one aspect ofhypertopia, the corneal surface is flattened which decreases the angleof refraction of rays as they pass through the refractive surfaces ofthe cornea, causing a convergence or focus of the rays at a point behindthe retina. The retina is comprised partially of nerve fibers which arean expansion of the optic nerve. Waves of light falling on the retinaare converted into nerve impulses and carried by the optic nerve to thebrain to produce the sensation of light. To focus parallel rays on theretina, the hyperopic eye must either accommodate, i.e., increase theconvexity of its lens, or a convex lens of sufficient strength to focusrays on the retina must be placed before the eye.

Myopia is that refractive condition in which, with accommodationcompletely relaxed, parallel rays are brought to focus in front of theretina. One condition which commonly causes myopia is when the cornealcurvature is steepened, thus the refraction of rays is greater as theypass through the refractive surfaces of the cornea, and the overrefracted rays converge or focus in front of the retina in the vitreousof the eye. When the rays reach the retina they become divergent,forming a circle of diffusion and consequently a blurred image. Aconcave lens is used to correct the focus of the eye for myopia.

The normal treatment of these classic forms of refractive error of theeye is with the use of eyeglasses or contact lenses, both of which havewell-known disadvantages to the user. Recent research has been directedto operative techniques to change the refractive condition of the eye.Such techniques are generally referred to "keratorefractive techniques".Two such techniques are more particularly called keratophakia andkeratomileusis. Keralomileusis involves the regrinding of a corneallamella into a meniscus or hyperopic lens to correct myopia orhyperopia. A corneal optical lathe has been especially developed forthis procedure and is also used in the keratophakia procedure, when ahomograft ground into a convex lens is placed interlamellarly to correctaphakic hypermetropia. The homograft tissue (corneal lamella) is frozenwith carbon dioxide. The homograft is cut as a contact lens would be,i.e., to the optical power required to effect the desired opticalcorrection of the cornea. In keratomileusis, the anterior corneallamella is shaped by the lathe and in keratophobia, it is the cornealstroma of a donor eye that is shaped by the lathe. These techniques havea broad application in the correction of high hyperopic and myopicerrors. These procedures require radial cutting of the cornea about theperiphery of the graft which weakens the cornea so that pressure fromfluids below the incisions pushes up under the cuts and flattens thecurvature of the cornea. This flattening of the cornea results inrefractive errors to the eye not compensated for by the graft. Suturingin these operations also causes radial asymmetry of the corneaconsequently promotes astigmatic error in this regard. Sutures alsocause scarring of the corneal tissue, which scar tissue loses itstransparency. Surgical correction of astigmatism is accomplished byasymmetrically altering the corneal curvatures. The effect of aperipherical distorting force may be easily visualized by imagining aninflated balloon with a spherical surface being compressed between thepalms of the hands. Because the volume of air in the balloon isconstant, the surface area remains constant. The previously sphericalanterior surface is distorted meridianally as a result of compressingthe diameter between the hands so that the curvature changes withoutchanges the circumference of the surface. The meridian passing over theballoon between the extended fingers steepens, while the uncompressedmeridian at right angles thereto flattens as its diameter lengthens inproportion to the shortening of the compressed diameter. Thisdemonstrates the effect that may result from slight variations in thesymmetrical patterns or intentional asymmetrical patterns attempted tobe accomplished during surgical procedures and attendant suturing. It isthus seen that present procedures in keratorefractive techniques arebest limited to situations where other more standard correctivepractices are found ineffective. It is readily seen that the limitingfactors in such surgical techniques is the gross complexity involved notonly with multiple incisions in corneal tissue for affecting theprocedures but also complex suturing patterns, resulting in grossrestructing of the eye. The eye is thus faced with a difficult job ofadjusting to this trauma.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a new andimproved keratorefractive surgical technique involving method andapparatus for changing the shape of the optical zone of the cornea tocorrect refractive error whereby a minimum disturbance is imposed on theeye system and the simplicity of the technique virtually eliminates thechance of error or further complications resulting from grossdisturbances of the eye system.

With this and other objects in view of the present inventioncontemplates a method and apparatus involving inserting one end of asplit end adjusting ring in the cornea of the eye and moving the ring ina circular path until its ends meet, whereby the ends are adjustedrelative to one another until the shape of the eye has assumed a desiredcurvature whereupon the ends are fixedly attached to maintain thedesired curvature of the cornea.

Another aspect of the invention involves an adjusting ring which wheninserted in the cornea is arranged to have its major cross sectionalaxis aligned or substantially parallel with a corneal arc extendingthrough the anterior pole of the cornea.

An important aspect of the invention is directed to the use of anadjustment ring holder which is capable of being positioned about thecornea so as to orient a dissecting and/or adjustment ring to have itsmajor cross sectional axis to be aligned or substantially parallel tothe corneal arc formed by the anterior pole of the cornea as the holderis rotated.

A yet further aspect and object of the invention is to provide acombination dissecting/adjustment ring in which the forward end thereofdissects or parts the stroma portion of the cornea as the adjustmentring is inserted. Once inserted, the ring is adjusted to create withinthe cornea, the desired optical correction for that patient.

In still a further object of the invention, one embodiment provides fora drive ring is interconnected with the dissecting/adjusting ring at oneend while the other end is interconnected with a ring holder. Rotationof the ring holder and attached drive ring and the interconnecteddissecting/adjusting ring is rotated until the dissecting/adjusting ringhas been fully inserted into the cornea after which reverse rotationwill leave the adjusting ring in place while removing the drive ring.

A further aspect and object of the invention is directed to adissecting/adjustment ring and an edge coiled drive ring which arepreformed at a bevel or slope substantially corresponding to the slopeof the corneal arc formed by the anterior pole of the cornea.

A further object of the invention is to provide a ring holder thatincludes means for orienting a dissecting adjustment ring and/or a drivering at a slope substantially corresponding to the slope of the cornealarc of the anterior pole of the cornea.

A further aspect of the invention is directed to a holder that has meansat the bottom thereof for properly positioning and maintaining theholder at a desired axis to the cornea. At the bottom of the holder aremeans to retain an adjustment ring and/or an associated drive ring whichare predisposed at a slope substantially corresponding to the slope ofthe corneal arc formed by the anterior of the cornea. The holder ispositioned within a cylindrical top portion of a transparent guide cupso as to be rotatable therein. The cylindrical top portion is connectedto a bottom semi-spherical skirt of larger diameter than said topportion. An interior shoulder is formed at the junction of the topportion and the skirt to rotatably support the holder so as to beoriented relative to the cornea for the insertion of the adjusting ring.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a horizontal section of the eye.

FIG. 2 is a schematic illustration of an eye system showing adjustmentof the cornea to steepen the corneal slope.

FIG. 3 is a schematic illustration of an eye system showing adjustmentof the cornea to flatten the corneal slope.

FIG. 4 is a detailed schematic illustration of a horizontal section ofthe frontal portion of the eye showing an adjustment ring of thisinvention positioned in the stroma of the cornea.

FIG. 5 is a plan view of a combination dissecting/adjustment ringshowing its end portions.

FIG. 6 is a sectional view taken along the line 6--6 of FIG. 5.

FIG. 7 is a sectional view taken along the line 7--7 of FIG. 5.

FIG. 8 is a perspective view of the dissecting head of thedissecting/adjusting ring taking along the line 8--8 of FIG. 5.

FIG. 8A is a sectional view taken along the line 8A--8A of FIG. 5.

FIG. 9 is a top elevational view of a coiled drive ring used to drivethe dissecting/adjusting ring of FIG. 5.

FIG. 10 is a sectional view taken along the line 10--10 of FIG. 9.

FIG. 11 is an exploded view of a ring holder apparatus used in thisinvention.

FIG. 11A is an alternate embodiment of a guide cup.

FIG. 12 is a sectional view of the assembled ring holder of FIG. 11.

FIG. 12A is a sectional view of the aforedescribed ring holder of FIG.11 depicting an alternative embodiment of a ring orientation tool.

FIGS. 12B and 12C show respective front and side elevational views ofthe ring orientation tool of FIG. 12A.

FIG. 13 is a partial sectional view of the bottom of the ring holder.

FIG. 14 is a bottom elevational view taken along the line 14--14 of FIG.13.

FIG. 15 is a bottom elevational view of a ring support cup used inconjunction with the ring holder of this invention.

FIG. 16 is a sectional view taken along the line 16--16 of FIG. 15.

FIG. 17 is a partial bottom elevational view of the ring holder of thisinvention with the ring support and assembly cup and drive ringassembled therewith.

FIG. 18 is a bottom elevational view taken along the line 18--18 of FIG.17.

FIG. 18A is a partial view bottom plan of an alternative embodiment.

FIG. 18B is a view, partly sectional, taken along the line 18B--18B ofFIG. 18A.

FIG. 18C is a sectional view taken along the line 18C--18C of FIG. 18A.

FIG. 18D is a partial sectional view showing an alternate means forinner connecting the ends of the adjustment ring.

FIG. 19 is a sectional view taken along the line 19--19 of FIG. 18.

FIG. 20 is a top elevational view of dissecting ring capable of use withthe ring holder of this invention.

FIG. 21 is a sectional view taken along the line 21--21 of FIG. 20.

FIG. 22 is a partial sectional view taken along the line 22--22 of FIG.21.

FIG. 23 is a top elevational view of an adjustment ring for use inconjunction with the dissecting ring of FIG. 20.

FIG. 24 is a sectional view taken along the line 24--24 of FIG. 23.

FIG. 25 and FIG. 26 are top elevational views of dissecting andadjustment rings as described in U.S. Pat. No. 4,452,235.

FIG. 27 is a bottom sectional view of another embodiment of a ringholder.

FIG. 28 is an elevational view of the ring holder of FIG. 27 includingthe assembled dissecting or adjustment ring.

FIG. 29 is a schematic view describing one method for forming the slopeddrive or dissecting ring of this invention.

FIG. 30 is a side elevational view of a releasable clip used to connectthe ends of an adjustment ring.

FIG. 31 is an elevational view of an instrument used to mark the corneato identify the incision lines for the surgeon.

FIG. 32 is a top sectional view taken along the line 32--32 of FIG. 31.

FIG. 33 is a bottom plan view taken along the line 33--33 of FIG. 31.

FIG. 34 is a partial section view taken along the line 34--34 of FIG.32.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Before explaining the present invention in detail, it is to beunderstood that the invention is not limited to its application to thedetails of construction and arrangement of parts illustrated in theaccompanying drawings, since the invention is capable of otherembodiments and of being practiced or carried out in various wayscommensurate with the claims herein. Also it is to be understood thatthe phraseology or terminology employed herein is for the purpose ofdescription and not of limitation.

Referring first to FIG. 1 of the drawings, a horizontal section of theeye shows the globe of the eye resembling a sphere with an anteriorbulged spherical portion 12 representing the cornea. Thus the eye isactually comprised of two somewhat modified spheres placed one in frontof the other. The anterior of these two segments is the smaller morecurved cornea.

The globe of the eye consists of three concentric coverings enclosingthe various transparent media through which the light must pass beforereaching the sensitive retina. The outermost covering is a fibrousprotective portion the posterior five-sixths of which is white andopaque and called the sclera 13, and sometimes referred to as the whiteof the eye where visible to the front. The anterior one-sixth of thisouter layer is the transparent cornea 12.

A middle covering is mainly vascular and nutritive in function and iscomprised of the choroid 14, cibiary body 15 and iris 17. The choroidgenerally functions to maintain the retina. The ciliary muscle isinvolved in suspending the lens and accommodation of the lens. The irisis the most anterior portion of the middle covering of the eye and isarranged in a frontal plane. It is a thin circular disc corresponding tothe diaphram of a camera, and is perforated near its center by acircular aperture called the pupil 19. The size of the pupil varies toregulate the amount of light which reaches the retina. It contracts alsoto accommodation, which serves to sharpen the focus by diminishingspherical aberration. The iris divides the space between the cornea 12and the lens 21 into an anterior chamber 22 and posterior chamber 23.The innermost portion of covering is the retina 18, consisting of nerveelements which form the true receptive portion for visual impressions.

The retina is a part of the brain arising as an outgrowth from thefore-brain, with the optic nerve 24 serving as a fibre tract connectingthe retina part of the brain with the fore-brain. A layer of rods andcones, lying just beneath a pigmented epithelium on the anterior wall ofthe retina, serve as visual cells or photoreceptors which transformphysical energy (light) into nerve impulses.

The viterous 26 is a transparent gelatinous mass which fills theposterior four-fifths of the globe. At its sides it supports the ciliarybody 16 and the retina 18. A frontal saucer-shaped depression houses thelens 21.

The lens 21 of the eye is a transparent bi-convex body of crystallineappearance placed between the iris 17 and viterous 26. Its axialdiameter varies markedly with accommodation. A ciliary zonule 27,consisting of transparent fibers passing between the ciliary body 16 andlens 21 serves to hold the lens in position and enable the ciliarymuscle to act on it.

Referring again to the cornea 12, this outermost fibrous transparentcoating resembles a watch glass. Its curvature is somewhat greater thanthe rest of the globe and is ideally spherical in nature. However, oftenit is more curved in one meridian than another giving rise toastigmatism. A central third of the cornea is called the optical zonewith a slight flattening taking place outwardly thereof as the corneathickens towards it periphery. Most of the refraction of the eye takesplace on the surface of the cornea.

Referring to FIG. 4, a more detailed drawing of the anterior portion ofthe globe shows the various layers of the cornea comprising anepithelium 31. Epithelian cells on the surface thereof function tomaintain transparency of the cornea. These epithelia cells are rich inglycogen, enzymes and acetylcholine and their activity regulates thecorneal corpuscles and controls the transport of water and electrolytesthrough the lamellae of the stroma 32 of the cornea.

An anterior limiting lamina 33, referred to as Bowman's membrane, ispositioned between the epithelium 31 and the substantia propia or stroma32 of the cornea. The stroma is comprised of lamella having bands offibrils parallel to each other crossing the hole of the cornea. Whilemost of the fibrous bands are parallel to the surface, some are oblique,especially anteriorly. The fibrous bands within alternate lamella are ata near right angle to bands in the adjacent lamella. A posteriorlimiting lamina 34 is referred to as Descement's membrane. It is astrong membrane sharply defined from the stroma and resistant topathological processes of the cornea.

The endothelium 36 is the most posterior layer of the cornea andconsists of a single layer of cells. The limbus 37 is the transitionzone between the conjunctiva 38 and sclera 13 on the one hand and thecornea 12 on the other.

Referring next to FIG. 2 of the drawings, the globe of an eye is shownhaving a cornea 12 with a typical patient's normal curvature representedby the solid line 39. If parallel rays of light 41 pass through thecorneal surface 39 of FIG. 2 they are refracted by the corneal surfacesto converge eventually near the retina 18 of the eye. The diagram ofFIG. 2 discounts, for the purposes of this discussion, the refractiveeffect of the lens or other portions of the eye. The eye depicted inFIG. 2 is hyperopic (far-sighted) and thus the rays of light 41 arerefracted to converge at point 42 behind the retina. If a peripheralband of pressure is applied inwardly at the chord 43 of the cornea, thewalls of the cornea are caused to steepen. This is because the volume offluids within the anterior chamber 22 remains constant, thus theanterior portion of the cornea, including the optical zone (inner thirdof the cornea) steepens in slope to form a curvature (shown inexaggeration) following the dotted line 44. The rays of light 41 arethen refracted from the steeper surface 44 at a greater angle to directthe refracted rays into focus at a shorter distance, such as directly onthe retina 18.

FIG. 3 shows a similar eye system to that of FIG. 2 except that the socalled normal corneal curvature of FIG. 3 causes the light rays 41 torefract into focus at a point 46 in the vitreous which is short of theretinal surface 18. This is typical of a myopic (nearsighted) eye. Ifchord 43 of the cornea is expanded uniformly outwardly as shown by thearrows, the walls of the cornea are flattened. Light rays 41 refractedby the now flattened corneal surface will be refracted at a smallerangle and thus converge at a more distant point such as directly on theretina 18.

The methods and apparatus of the present invention are concerned with asystem for adjusting an annular chord of the cornea as suggested by theprocesses shown in FIGS. 2 and 3 to thereby correct refractive errors ofthe eye. Again referring to FIG. 4, a ring 47, having an ovaloid crosssectional shape is shown implanted in the stroma layer of the cornea. Byadjusting the diameter of such a ring in the cornea and fixing thatdiameter at a discrete value, the rays refracted by the cornea and othereye components can be brought to focus directly on the retina 18. Such aring placed typically at approximately the 8 mm chord of the corneaprovides a means for making such a corrective adjustment. Apparatus andmethods for making this adjustment are hereinafter described.

Referring now to FIGS. 5, 6, 7 and 8, the adjusting ring 47 is comprisedof a generally circular member having split end portions 48 and 49. Thering is comprised of a material which has sufficient stiffness tomaintain its generally circular shape and sufficient resiliency topermit ends 48 and 49 to be adjusted relative to one another to therebyenlarge or decrease the normal diameter of the ring at rest. Thematerial should have properties that render it physiologicallycompatible with the tissue of the cornea. Two such materials are ofplastic sold under the trademarks PLEXIGLASS and SAUFLON. Generally,materials made of hardened methyl Methacrylate or the like areacceptable. The forward end portion 48 of the adjusting ring 47 isenlarged to form a leading dissecting sharpened edge which, as it isdriven through the stroma 32 of the cornea forms a tunnel for thetrailing ring. The purpose of the enlarged edge as shown is to include aU-shaped opening 50 which is adapted to receive a drive ring as shown inFIGS. 9 and 10 for driving the ring into the cornea, provide clearancefor the removal of the guide tool yet leave the plastic adjusting ringin situ within the cornea. The cross-sectional shape of the ring, asshown in FIGS. 6 and 7, comprises top surface 52 and a bottom surface 54which are substantially parallel, and connected at their inner ends by aV-shaped rib 56 and at the outer end a V-shaped rib 58. In a preferredembodiment, the V-shaped ribs are formed by 45° intersecting surfaces,but could be at other intersecting angles. Of particular importance, isthe forming of the adjusting ring such that the major axis of the ringis at an angle N which substantially corresponds to the slope of thecorneal arc of the anterior pole of the cornea. Typically, this has beenfound to be an angle of 22-1/2 degrees but varies from patient topatient. An opening 60 is provided adjacent to leading edge ofadjustment ring 47 while a plurality of spaced openings 62 are found inthe trailing edge. Once the adjusting ring has been in position, therequired adjustment is retained by adhesives or by the insertion of aU-shaped clip 64 shown in FIG. 30.

Referring now to FIGS. 9 and 10, where is shown a drive ring 70 of theinvention used to push and insert the adjusting ring 47 into itsposition. The ring is formed as a helical coil for use with the ringholder as hereinafter described. The drive ring has a leading edge 72(see FIG. 12) terminating with an upright member 74 or other means forattachment and retention of the drive ring within a ring holder of thisinvention. As shown in FIG. 10, the ring is formed at a slope angle Nsubstantially corresponding to the slope of said corneal arc asdescribed for the adjustment ring. The cross-section of the ring isgenerally rectangular having a top side 76 and a bottom side 78 with aninterior V-shaped groove 80 formed to match the V-shaped rib 56 of theadjusting ring. Preferably, the groove is formed by two 45° intersectingsurfaces. One method of forming the edge coiled helical ring isschematically described in FIG. 29.

FIGS. 11, 12, 13 and 14 describe one form of ring holder of theinvention which is adapted to retain and rotatably insert a curvatureadjusting ring into the cornea of a patient's eye and is generallydesignated by the numeral 90. The holder is also adaptable to insert adissecting ring followed by the insertion of an adjusting ring such asis described in related U.S. Pat. No. 4,452,235. However, the preferreduse is to insert an adjustment ring such as described herein FIGS. 5-8which ring includes a dissecting head. The holder is generallycylindrical having a top 92 and a bottom 94 and of diameter for useabout a patient's eye. The bottom 94 includes means to releasably retainthe adjustment ring and/or drive ring. The interior of the holder issubstantially a hollow cylinder forming interior walls 96, shown by thedotted lines, which intersect thereabove with a smaller diameter opening98, also shown dotted. A plurality of openings 100 are provided adjacentthe lower end above a rim 102. The openings 100 are provided for thevisual inspection by the surgeon during the operation. A guide cup,generally indicated by the numeral 106, is preferably made of a clearplastic material, again for the visual inspection by the surgeon, andcomprises a cylindrical top portion 108 adapted to rotatably receive thebottom end of holder 90 which rests upon an interior shoulder 110. Thecylindrical portion 108 is connected to a bottom semispherical skirt 112having an inside curved surface 111 which may include a serrated bottomedge 114 or separately flexible fingers 115 (FIG. 11A) which surface111, in its preferred use, is of a diameter so as to be positioned uponthe limbus portion of the patient's eye permitting the cornea to becentered therein. An opening 116 is provided that extends both into thespherical skirt 112 and the cylindrical portion 108, again to providevisual acuity to the surgeon during the operation. A removable ringorientation blade, generally indicated by the numeral 120 includes ahandle 122, a shaft 124 and a curved blade 126 shown dotted on theinterior of the holder 90. The purpose of the blade can best bedescribed with reference to the assembly view of FIG. 12 in that it isadapted to orient the tip of the dissecting blade and/or adjusting ringto enter the first incision in the corneal surface. The orientationblade 120 is thereafter removed and the rotation of the drive holder 90causes the plastic ring to enter the stroma of the cornea and be guidedproperly thereby.

FIG. 12A describes an alternate embodiment of ring holder 300 andassociated ring guide and orientation tool, generally designated by thenumeral 302. The ring holder 300 is shown inserted into guide cup 106,previously described. FIGS. 12B and 12C depict the tool 302specifically. The tool is made of plastic material, e.g. polyethylenewhich functions with a scissor-like movement caused by the shape. Twoupper arms 304 and 306 are interconnected at a hinge 308 having opening309 to two lower arms 310 and 312, the former of which has an outwardtip 314. The upper arms 304 and 306 include respective stop pins 320 and322. The function of the tool 302 is best shown in FIG. 12B. The inwardmovement of arms 304 and 306 causes a corresponding inward retractingmovement of arms 310 and 312. In the retracted, dotted line, positionthe tool can be inserted into the tool holder 300. Releasing the armscauses the reverse outward movement permitting the tip 314 to beoriented relative to the drive ring 70 as shown in FIG. 12A, so that thedrive ring 70 will be angularly oriented relative to the cornea. Stoppins 320 and 322 rest upon the top of holder 300, the location of whichorients the ultimate position of tip 314. Upon rotation of the holder300, the adjustment ring will be caused to enter the stroma at theproper incision angle.

As shown in the embodiment of FIGS. 13 and 14, the bottom rim 102 of thering holder 90 includes a plurality of spaced ledges 130A and 130B whichare provided to receive the coil of the dissecting and/or drive ring 70with the insertion end to be ultimately oriented at the proper incisionangle to the cornea. One of the ledges includes a space 131 to receivethe upright portion 74 of the drive ring 70 shown partially in phantomview. The means shown is not limiting as other means to attach the drivering may very well be suggested.

Referring now to FIGS. 15 through 19 an additional embodiment of theinvention is disclosed as a utilizing guide cup 160 as a means to orientthe drive/adjustment rings at the proper incision angle. The cup ispositioned at the bottom of holder 90. The cup is circular in shape andsplit forming a leading edge 152 and a trailing edge 154. The cup isformed of a curved lip 156 around its outer periphery to fit over thebottom of rim 102 of holder 90 as shown in FIG. 17. The inner portion160 is formed as a straight slope substantially corresponding to theslope N of the corneal arc of the anterior pole of the patient's cornea.At the center of the cup is an opening 162. The purpose of the guide cupcan best be explained with reference to FIGS. 18 and 19 being to givesupport to ring 70 of FIG. 9 while hand assembling the adjustment ring47 of FIGS. 5-7 into the vee groove 80 of drive ring 70 shown in FIGS. 9and 10. Once assembled, the cup 150 is removed from the holder prior tosurgery. The top elevational view of FIG. 18 describes the assembledcombination.

In the operation and use of this embodiment, the drive ring 70 wouldfirst be installed into the bottom rim 102 of holder 90. Thereafter, orpreviously thereto, the guide cup would be positioned at the bottom 94of holder 90 threading the drive ring 70 such that it would be exposedupon surface 160 for at least one revolution. Thereafter, the cornealdissecting-adjusting ring 47 would be assembled to the drive ring suchthat rib 56 of the adjustment ring snuggly fits within groove 80 of thedrive ring as shown in FIG. 19.

FIGS. 18A, 18B and 18C depict one embodiment wherein the trailing end 58of adjustment ring 52 is radially compressed to a position under theforward portion of ring 52. A keeper sleeve 77, as shown, is positionedbelow the forward and initial entry portions of drive ring 76 andadjusting ring 52, which retains the adjustment ring and the drive ring76 together until the surgical process of inserting the ring iscomplete. The keeper is a rectangular housing open at the forward end 79and closed by a stop member 81 for half of the rearward end 83. Thetrailing end 58 abuts against the stop 81.

Prior to the actual insertion of the adjustment ring the cornea ismarked using a tool 300, shown in FIGS. 31-34. The tool 300 iscylindrical with a series of points or serration 302 exposed at thebottom. Interiorly of the tool are a pair of intersecting cross-hairs304 and 306 which permit the surgeon the align the tool relative to agiven mark on the cornea. An incision marker 308 is at the bottom at anangle, e.g. 45° to the longitudinal axis of the tool 300. The marker 308includes incision points 310 and 312 which extend downward. In use anon-toxic dye is used to cover the serrations 302 and point 310 and 312.The tool is then aligned and pressed against the cornea. The imprint of310 and 312 provide a guide for the initial incision slit in the corneawhich will become the place of entry for the adjustment ring 48. Theactual entry is typically at about 80% of the depth from the anterior ofthe stroma.

Another embodiment of an adjustment ring interlock means is shown inFIG. 18D. The forward end includes a tapered opening 49 into which therounded trailing end 47 is inserted once the adjustment ring 52 has beenimplanted within the cornea. The embodiment would necessarily applywhere the adjustment ring size is already predetermined for a given eyecorrection. Thus assembled, holder 90 is then placed within guide 106such that the bottom 94 rests upon rim 110 with the exposeddissecting/adjusting ring and drive ring positioned therebelow into thespherical skirt 112. This assembly is then positioned over the cornea ofthe eye at the place where the incision is to begin. The surgeon viewingthrough the translucent guide 106 and particularly through visual aidopening 116 is able to begin the incision by rotating holder 90. Uponsuch rotation, the dissecting head 51 prepares a path through the stromaof the cornea at the proper slope and rotated approximately onerevolution. The holder is then reversed in direction permitting thedrive ring to be rotated without the dissecting-adjusting ring beingremoved. Thereafter, through appropriate instrumentation and direction,the surgeon will adjust the ring by placing an appropriate U-shaped clip64 into opening 60 and whatever opening 62 of the trailing edge 49 thatwill provide the correct corneal curvature adjustment.

Referring now to FIGS. 20, 21 and 22, an alternate embodiment of theinvention is disclosed for use with the holder 90 of this invention. Inthis embodiment, an edge coiled ring generally designated by the numeral180 is coiled, as shown in FIG. 21 at a slope N. The forward end of thering includes an enlarged sharpened end 182 forming the cutting surfacefor forming the pathway within the stroma of the cornea by the rotationof the holder 90 in the manner previously described. The rearward end ofthe coil includes an upright portion 184 for attachment within the space131 (FIG. 13). Following the pathway formed by the dissecting ring andits remover the holder is then adapted to receive an adjustment ring asshown in FIGS. 23 and 24 or FIGS. 25 and 26 as described andincorporated herein by reference to U.S. Pat. No. 4,452,235. Theadjusting ring is formed at a slope N and comprises an outer surface 186and an inner surface 188. An opening 188 is provided at one end of theadjustment ring with a slot 190 and a plurality of openings 192 within aslot 194 to receive a clip 64 such as shown in FIG. 30 after theappropriate adjustment has been made.

FIG. 25 depicts a dissecting ring as described in the aforesaid U.S.Pat. No. 4,452,235 while FIG. 26 describes the adjusting ring which isalso shown and described in the aforesaid patent.

FIG. 27 is a cross-sectional view of an alternate embodiment of theinvention of a holder 200 having at its end therein means to receive adissecting and adjustment ring such as shown in FIGS. 20 through 26. Theend of the holder is sloped at an angle N substantially equivalent tothe corneal arc of the anterior pole of the cornea. Incorporated thereinis a groove 204. The groove is of sufficient depth and width to supporta dissecting and adjustment ring in radial compression yet release saidring at an appropriate time in the surgical operation.

FIG. 29 is descriptive-schematic of a cold form process to form the edgecoiled drive ring 70 or dissecting ring 182 of FIG. 20. In this process,the starting material is a steel wire 220 shown in circularcross-section at 222 which is forced through forming rollers 224 and 226to form the rectangular cross-section 228. The forceful movement of thematerial is continued through a forming die 230 which edge coils thematerial and bends same to the desired slope N. Thereafter, asschematically shown, sections of the edge coiled material are cut as,for example, in 21/4 turns at station 236 followed by the formation oftip 74 at station 238. Thereafter the edge coiled material is heattreated at 240 followed by necessary deburring and polishing 242.

We claim:
 1. A curvature adjusting ring for insertion into the cornea ofan eye comprising a forward end and a rearward end, means on saidforward end to dissect a circular pathway in said cornea to receive saidadjusting ring, and said adjusting ring having a cross-sectional shapecomprising a nonequilateral hexagon with opposing parallel longer sides,wherein the longer sides of the hexagon define a top surface and abottom surface of the curvature adjusting ring, wherein the bottomsurface is at an angle N which substantially corresponds to the slope ofthe anterior surface of said cornea, and means to interconnect the endsof said ring.